Quaternized fatty acid triethanolamine ester salts are cationic surfactants which are excellent fabric-softeners that have high ecotoxicological compatibility. Ester quats are typically produced in a two-stage process in which triethanolamine is first partly esterified with fatty acids and the reaction product is subsequently alkylated or quaternized with an alkylating agent. Hypophosphorous acid and sodium hypophosphite are preferred catalysts for the esterification step. However, during working up, particularly at relatively high temperatures, certain by-products are formed, resulting in an adverse effect on the odor of the quaternized product. The present invention provides a process for the production of quaternized fatty acid triethanolamine ester salts having minimal odor problems. More specifically, the invention provides a process for the minimization of volatile organic sulphur byproducts in dimethyl sulfate quaternization of amines made with hypophorous acid, which leads to the formation of an odor stable product.